Multiple-station telephone system.



No. 805,126. PATENTED NOV. 21, 1905. A. J. PARMER. MULTIPLE STATION TELEPHONE SYSTEM.

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I f arlzey PATENTED NOV. 21, 1905.

A. J. FARMER. MULTIPLE STATION TELEPHONE SYSTEM.

APPLICATION FILED DEG.26, 1903.

3 SHEETS-SHEET 2.

mw mN No. 805,126. PATENTED NOV. 21, 1905.

I A. J. PARMER.

MULTIPLE STATION TELEPHONE SYSTEM.

APPLIGATION FILED DEO,26,1903.

3 SHEETS-SHEET 3.

IIIIIIIIIIIII UNITED sTATEs PATENT oEEroE.

MULTIPLE-STATION TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Nov. 21, 1905.

Application filed December 26, 1903. Serial No. 186,538.

To a, whom it may concern.-

Be it known that I, ARTHUR JoHN FARMER, a citizen of the United States of America, and a resident of- Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Multiple- Station Telephone Systems, of which the following is a specification.

My invention relates to improvements in multiple-station or party-line telephone systems, and has for its object the provision of means for selectively connecting and calling the desired station for effecting the proper sequence of signals at the exchange and thereafter automatically restoring the selective apparatus to normal or initial position and otherwise simplifying and rendering more effective the connection, selection, and restoration of telephone-lines'of this class.

The selective feature of my system I obtain principally by interposing between the central office and the several parties served by a given exchange-line an appliance which I shall term a junction-box, the same containing switching mechanism for connecting in circuit all of the stations upon the line or associated therewith or merely a given station or group of stations out of the entire number. The actuation and restoration of the junction-box apparatus are controlled by the exchange-operator through a key or switch appliance controlling the sources of current in a common-battery exchange system, or the restoration may be automatically accomplished by introducing into the cord-circuit suitable apparatus controlled by the calledsuloscribers switclrhook.

In selecting a party, current preferably is transmitted to the junction-box over both sides of the line to ground, while for effecting its restoration but one side is used, the appliance including means for checking it in its normal position for calling or receiving a call from any of the parties. To meet the added functions, the central-office apparatus is modified slightly, including therein relay mechanism and a source of current, preferably pulsating, automaticallyconnected in circuit with the junction-box apparatus when the line requires restoration to normal condition. My invention, however, will be more readily understood by making reference to the accompanying drawings, illustrating apparatus and a telephone system equipped in accordance therewith, wherein Figure 1 shows in plan view the junctionboX appliance adapted for switching the Va rious subscribers into and out of circuit. Fig. 2 is a side elevation of the same. Fig. 3 is a detail view illustrating the preferred form of switching-contacts with a portion of the contact-making drum employed therein; and Figs. 4 and 5, respectively, show in diagram ten subscribers circuits associated with the junction-box and its metallic-circuit exchange-line, and the modified central-office apparatus so far as it pertains to the calling side of the cord-circuit, the multiple jacks being duplicated in the two figures better to indicate the relation of these diagrams.

The same character of reference is employed throughout the drawings to indicate similar parts or diagrammatic representations 7 thereof.

Having given above a general statement as to the system of my invention, the details of its embodimentdescribed herein will be more readily grasped by firstsetting forth the structure of the junction-box. (Shown in Figs. 1

I have chosen to base my description on the assumption that ten parties, connected two by two, are to be served by a given exchangeline, and accordingly five sets of contact-making springs 1 1 to 5 5 are provided in the junction-box, eachof which is adapted to control one limb of its party-line. An additional set of contact-springs eis utilized for governing the circuit through the actuating electromagnet on.

Fig. 3 illustrates the preferred form of springs used herei n, with the exception merely of the set a, which requires normally open or back contact-making springs, as indicated in Fig. 2i. 0., in the normal or initial position of the junction-box. Thus set 1, for example, is seen to comprise two relatively long flexible springs mounted on the insulating base of the device, the inner one of which is 'crimped or provided with a projection or elevation adapted to be engaged by the pins 0 on the drum 5 to flex said springs and effect a rubbing contact therebetwcen. Accordingly all contacts in the j unction-boX are made between the stationary spring parts and do not depend on sliding or relatively movable contact parts.

Mounted on a common shaftt before these sets of contact-making springs are the controlling-pin-bearing disksf and 1 1 to 5 5, arranged in pairs, but each controlling its own set of springs. Four projecting pins diametrically disposed in varying relation are borne by each of the paired disks, those upon the pairs being identical, so that when the controlling-drum s, "formed of said disks, is in any other than normal position but two sets of springs corresponding to the two paired disks are closed together. Thus springs 3 and 3", respectively engaged by the pins in disks 8' and 3, are shown flexed into engagement to connect the corresponding line conductors with thecxchange. In the initial position or positions, however, the transverse row of pins 0 engages each its corresponding spring, opening contacts a and closing the remainder of the circuits in the junction-box controlling the party-lines.

At the outer end of the shaft 6 is mounted the ratchet-wheel r, operated through pawl p by the pivoted armature of the electromagnet m. The teeth upon said wheel indicate and correspond to the several operative positions of the controlling-drum. In the preferred type of apparatus one step of the ratchetwheel is designed to open one pair of contacts and close the adjacent pair, or, assuming the drum to be in the initial position, it will break contact between all pairs of springs excepting only springs 1 and 1", which will be momentarily separated and then immediately brought into contact again. If springs 5 and 5 be engaged by corresponding pins 0 instead, their contact will be broken momentarily and then, concurrently with a step of the ratchet, contact will be reestablished between springs 5 and 5", as well as between all the other sets of springs excepting c, which are opened. This places the junction-box in its normal or initial position.

Since there are live separate pairs of contact-springs to be actuated and one initial position is requisite, the drum must be rotatable into six operative positions. The range of movement of the ari'nature, however, is relatively small, and accordingly I have grouped all six positions upon the semicircumference of the drum by arranging the sets of pins to form the successive contacts between the springs on one half its circumference, the other half bearing similarly disposed or related contact-making pins adapted to duplicate the several operative positions. Accordingly there are two normal or initial positions out of the twelve operative positions of the drum. Likewise there are two in which each of the pairs of springs l l" and 2 and 2" are connected together, and so on. Thus in all but the initial positions two of the sets or pairs of springs are alternatively actuated into contact to close circuit with their corresponding line conductors in common with the closure of the circuit to the magnet m through the springs e.

The ratchet-wheel of the device necessarily is provided with twelve equidistant teeth, representing the twelve operative positions of the drum. It is perfectly obvious, however, that by altering merely the ratchet-wheel and adjustable pin-bearing disks to suit existing conditions different numbers of lines may be accommodated by the junction-box, and for this reason the drum is built up of disks whose contact-making pins or operative positions may be changed as required. I may state, however, that the arrangement described, employing duplicated contact-making pins upon each disk to avoid completely rotating the drum each time a station is selectively called, is the one to be preferred.

A back-stop pin 6, mounted on the standard 7, serves to determine the play or movement of the pawl p by reason of its engagement with the projection 8 thereon, thus checking the movement of the pawl, armature,

and ratchet-wheel each time in their proper positions. One of the pair of contacts 10 is secured to the base portion of the device, while the other is carried by the armature, the same being so positioned that they are in engagement with each other only during the reciprocation of said armature underthe influence of magnet m. An inclosed relay 9, whose windings are connected with one of the line conductors, is disposed upon the base adjacent to the actuating-magnet.

Further mechanical details of the junctionbox apparatus comprise a dog 11, bearing against the ratchet-wheel, and springs 12 13, acting, respectively, upon the pawl and armature, while a back-stop let serves as a rest for the armature when retracted by the spring.

The figures of the drawings, in connection with the foregoing description, set forth very plainly how the corresponding contact making and breaking pins, insulated in their respective disks, effect the opening of the circuit between springs e and the closure of circuit between the paired sets of springs in turn when rotated into engagement with the projecting portions of their respective springs.

Having gained an adequate idea of the mechanism for effecting the several circuit changes within the junction-box, reference to the remaing figures of the drawings will make clear the relation of the several parts and their cooperation in the system of my invention.

Fig. t will be recognized as a diagrammatic representation of ten telephone-stations 1 1 to 5 5, connected with the line conductors 15 16, extending to the exchange through the medium of the junction-box appliance previously considered. The use of the same characters of reference in the drawings will render the diagram largely SelfeXplanatory.

It will be observed that each station is connected with one or the other of the line conductors in a permanent manner, while connection with the other or opposite line conductor is controlled by an individual spring within the junction-box.

For example, line conductor 15 is continuhowever, that under the circumstances of use assumed a set or group of springs (comprising two pairs of springs, as 1- 1 is simultaneously actuated into and out of engagement. Hence stations 1 1 must together be connected in multiple with and disconnected from the line conductors.

The signaling-bells Z) at the several stations are respectively connected between one or the other of the line conductors and ground through the usual condensers 0", so that the operator can in the simplest manner possible selectively call the desired station when its group of two is connected in circuit, such connection necessarily being coupled with the disconnection of all the other groups except in the initial or normal position of the apparatus.

It is important to observe that in each case the ringing side of the station-line is the controlled limb of the circuit.

Relay 9 in the particular arrangement shown is permanently connected between conductor 16 and ground, while the actuating-electromagnet m is associated with line conductor 15 through the medium of any of the multiple. contacts e,'10, or 17, the first being the controllable contact-springs within the junctionbox, the second the auxiliary contacts directly actuated by the armature, and the third the contacts of relay 9. All of these are initially or normally separated.

The characteristics of the junction-box apparatus accordingly are seen to be such that the operator may by directing current over both line conductors in parallel with ground return step the contact-controlling drum from the initial position into any of the five operative positions wherein the stations are connected to line two by two for the purpose of selective signaling, whereas to return the junction-box apparatus to the initial position currentis directed over line conductor 15 only.

Having given attention to the foregoing, the reason for this will be apparent. In the initial position contact-springs e are separated, so that no current can reach magnet m until the relay-contacts 17 are closed. However, immediately the controlling-drum is advanced from its initial position circuit through the magnet m is established between contacts e,and the drum may be advanced through its several positions until initial position is again reached merely by directing current over line conductor 15. In order to insure the complete return to initial position, however, 1 preferably provide the auxiliary contacts 10, whiclrare closed during the movement of the armature and serve to afford an independent path for the current actuating the magnet and avoid the premature opening of the circuit by reason of the separation of springs c.

It will be understood that the several windings connected between the line conductors and ground are of such high impedance as to preclude the formation of a low-resistance bridge across the metallic line conductors.

A number of modifications of the standard calling side of the operators cord-circuit will be observed in the diagram given in Fig. 5. By-reason of these the operator is enabled to accomplish the results already alluded to, in

that she can after selectively signaling anystation return the junction-box apparatus to the normal or initial position either manually or automatically upon the subscriber hanging up his receiver. For the first purpose key 18 is pressed the requisite number of times to select the station, which is then rung by use of key 30 or 31, and when return to' the initial .position is desired the same key 18 is again pressed the number of times necessary to restore the junction-box apparatus. Switch 32 is provided for the purpose of sending current over one or both of the line conductors by way of key 18 and may be opened when manual restoration is resorted to for preventing the controlling-d rum from being actuated past the initial position. I will set forth, however, the preferred mode of effecting the restoration of the junction-box apparatus and automatically connecting all of the party-lines in circuit.

It will first be observed that the supervisory relay w, in addition to the usual contact 19 for controlling the signal-lamp, is equipped with the contacts 20 and 21 for efliecting a special purpose. In circuit with the lamp 23 and bat tery 22 is, provided a relay (1;, whose contacts 24 intermediately control a special circuit. Included in circuit with the cord 25 are the relay ;2 contacts 21 26, and source of intermittent current 27. Contacts 28 of the latter relay serve to open and close the answering side of the cord-circuit, while the contacts 27 are provided for the control of a shunt about the supervisory lam p 23. Another relay is connected in a local circuit, including battery 28 and contacts 20, provision being made for the closure of another circuit through the same whenever contacts 24 and 29 are simultaneously closed or when they are closed during the same period.

IIO

Since the restoring-current from source 27 ciated with the cord-circuit must be restored to normal condition upon the removal of the plug from its jack.

For the purpose of illustrating the Workings of my invention let us assume that the operator has received a call for subscriber 3 and trace out the various steps or circuit changes necessary to secure his connection in circuit and the return of the apparatus to normal condition.

Ordinarily all that is demanded of the operator is to plug into the desired jack, press three times on key 18, and then selectively ring the desired subscriber by means of ringing-key 31, which transmits current from generator 9, over line 16 and the bell of subscriber 3, to ground, the remainder of the operation normally being automatic. Should the party not answer, however, key 18 would be pressed three times more by the operator and the plug would be removed from the jack.

We will follow the operation, assuming that subscriber 3 answers his call. Upon plugging in current flows from grounded battery 22, through relay :1), to lamp 23, ring and thimble of the plug and jack, relay '0, and to ground, thereby insuring the closure of contacts 24 while the plug remains in the jack. Supervisory relay w is energized upon the subscriber answering his call and removing the receiver from its hook by reason of the lowresistance bridge across the line. Hence contacts 21 are opened and contacts 20 remain closed while subscriber 3 is talking. The latter contacts complete an independent circuit, including battery 28", through the windings of relay .2, and its contacts 26 and 29 are actuated into engagement. Contact 26, it will be seen, is one of the controlling contacts in the grounded circuit, including the source of intermittent current 27" and magnet m, for effecting automatic restoration. The closure of contacts 29 of relay .2 during the engagement of contacts 24 of relay w completes a separate circuit from battery 28 through relay .2, so that the latter will remain energized while the plug is in the jack. \Vhen subscriber 3 hangs up his receiver, the supervisory relay is at once deenergized, thus opening contacts 19 and 20 and closing contacts 21. The latter closes the circuit already partially established from the source of intermittent current 27, through contacts 26 and 21, the key-contacts and those of the. plug and jack to line conductor 15, thence to magnet on, where the current impulses serve to step the junction-box apparatus into initial position, whereupon the circuit to magnet m is broken in the manner before described and the apparatus remains at rest. \Vhile this is occurring, the intermittent cur rent is flowing through the windings of relay y, so that its contacts 27 are alternately closed and opened and contacts 28 simultaneously opened and closed, the one shunting the supervisory lamp and the other opening the cordcircuit to the answering side to prevent any restoring-current from reaching that side of the connection. Supervisory lamp 23, now normally lighted, is alternately extinguished and relighted by reason of the intermittent shunt until the j unction-box apparatus is completely restored, thus serving to warn the operator not to take down the connection until the lamp burns steadily as a proper signal therefor. Removing the plug upon getting the said signal of course restores the exchange apparatus to. normal condition, and, as explained, the several stations connected with the junction-box apparatus are left bridged across the main-line conductors, so that any one can signal the exchange in the well-known manner.

In the foregoing I have clearly set forth, I believe, the most desirable application of my invention; but I may merely allude to other advisable employments thereof. For example, the number of contact-springs in the junction-box and the corresponding operative positions are readily and very simply altered to meet existing requirements by adding or removing the springs and changing the contact-making disks upon the drum. The connection of the junction-box with the subscribers circuits likewise is subject to numerous alterations to meet varying conditions. Thus although practical privacy in the use of the line is obtained in the example given, since all the parties but one are disconnected during conversation and a selective signal is provided for, five parties may be given service with absolute privacy and over individual metallic lines, using the same apparatus, the contact-springs then controlling both limbs of the line. Twenty or any intermediate number of parties might, on the other hand, be connected to the apparatus for service should it be desired, selective calling being provided for simply by adopting the well-known polarized bells and corresponding means for ringing them. However, these and other modilications will be plain to those skilled in the art, and v I claim the following as setting forth my invention:

1. In a telephone-exchange system, the combination with a party-line switching appliance, of means provided in the cord-circuit at the exchange for sending actuating-current over both line conductors in parallel to said switching appliance, relay apparatus for sending current over one side of the line thereto, and means controlled by the removal of the connecting-plug for restoring the relay apparatus to normal condition, substantially as set forth.

2. Ina telephone-exchange system, the combination with a party-line switching appliance, of means provided at the exchange for sending actuating-current thereto, relay apparatus at the exchange for transmitting restoring-curmeans controlled by the subscribers switch-- hook for automatically actuating said relay apparatus, substantially as set forth.

3. In a telephone-exchange system, the combination with a party-line switching appliance, of means provided at the exchange for transmitting actuating-current thereto and effecting the selection of the desired station, relay apparatus in the cord-circuit controlling the transmitting-current, a portion thereof being operated upon the insertion of the plug and another portion by the subscribers switchhook, whereby the switching appliance is automatically restored to normal condition upon the conclusion of conversation, substantially as set forth.

4:. The combination with a telephone-exchange, of a multiple-station telephone-line extending therefrom affording a metallic talking-circuit, a plurality of substations normally connected thereto upon individual circuits, a third conductor or conducting medium uniting the exchange and each of the substations, and an electromagnetic switching appliance bridged between one of the line conductors and the third conductor, said appliance being connected to control the individual circuits, and provided with means for selectively connecting the associated circuits with the mainline or talking circuit, substantially as set forth.

5. In atelephone-exchange system, the combination with a party-lineswitching appliance, of the switchboard apparatus at the exchange for effecting its control and interconnection with other lines, the same including in the cord -circuit, a source of current, manual switching apparatus for transmitting current over both limbs of conductors connecting said party-line switching appliance, a source of intermittent current, relay apparatus connected therewith and with the cord-circuit, controlled by the subscribers switch-hook and adapted automatically to transmit current over one limb of the line to said switching appliance, whereby it is restored to normal condition, substantially as set forth.

a 6. In a telephone-exchange system, the combination with a plurality of subscribers lines, a party-line switching appliance governing the group, line conductors uniting it with the exchange, means provided at the exchange for sending actuating-current over both line conductors to said appliance, a source of intermittent current, and relay apparatus governed by the subscribers switch-hook for sending said current over one line conductor automatically to restore the switching appliance to normal condition, substantially as set forth.

7. In an intermediate substation telephone system, the combination with a rotatable stepby-step switching appliance, of means provided. at the exchange for transmitting actuating-current thereto to step the appliance into position for selecting any desired station, relay apparatus in the cord-circuit controlling the actuating-current, a portion thereof being connected to operate upon the insertion of the calling-plug at the exchange, and another portion to operate through the movement of the subscribers switch-hook, whereby the switching appliance is automatically restored to normal condition upon the conclusion of conversation, substantially as set forth.

Signed at Detroit, Michigan, this 11th day of December, 1903, in the presence of two subscribing witnesses.

ARTHUR J. FARh IER. Witnesses:

ANTHONY J. MoNNIG, JOHN E. LANGLEY. 

